Forged ink stick fabrication from in-line extrusion

ABSTRACT

A method of manufacturing an ink stick for use in a phase change ink jet imaging device comprises heating phase change ink material to an extrusion temperature at which the phase change ink material is in a malleable state. The heated ink material is then extruded through an extrusion orifice to form an extruded element. A forging element is then pressed against the extruded element to form an ink stick.

CROSS-REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly-assigned copending U.S. patentapplications Ser. No. 11/545,999, entitled “SOLID INK STICK FABRICATIONBY FIBER EXTRUSION” by Jones et al., Ser. No. 11/545,874, entitled“SOLID INK STICK FABRICATION BY EXTRUSION, ROLL FORMING AND SWAGING” byJones et al., and Ser. No. 11/546,084, entitled “FLOW FILL MANUFACTURINGOF SOLID INK STICKS WITH TOP SURFACE CONDITIONING” by Jones et al. eachbeing filed concurrently herewith, the disclosures of which areincorporated herein.

TECHNICAL FIELD

This disclosure relates generally to phase change ink jet printers, thesolid ink sticks used in such ink jet printers, and the methods used tofabricate such an ink stick.

BACKGROUND

Solid ink or phase change ink printers conventionally receive ink in asolid form, either as pellets or as ink sticks. The solid ink pellets orink sticks are placed in a feed chute and a feed mechanism delivers thesolid ink to a heater assembly. Solid ink sticks are either gravity fedor urged by a spring through the feed chute toward a heater plate in theheater assembly. The heater plate melts the solid ink impinging on theplate into a liquid that is delivered to a print head for jetting onto arecording medium. U.S. Pat. No. 5,734,402 for a Solid Ink Feed System,issued Mar. 31, 1998 to Rousseau et al.; and U.S. Pat. No. 5,861,903 foran Ink Feed System, issued Jan. 19, 1999 to Crawford et al. describeexemplary systems for delivering solid ink sticks into a phase changeink printer.

Phase change inks for color printing typically comprise a phase changeink carrier composition which is combined with a phase change inkcompatible colorant. In a specific embodiment, a series of colored phasechange inks can be formed by combining ink carrier compositions withcompatible subtractive primary colorants. The subtractive primarycolored phase change inks can comprise four component dyes, namely,cyan, magenta, yellow and black, although the inks are not limited tothese four colors. These subtractive primary colored inks can be formedby using a single dye or a mixture of dyes. For example, magenta can beobtained by using a mixture of Solvent Red Dyes or a composite black canbe obtained by mixing several dyes. U.S. Pat. Nos. 4,889,560, 4,889,761,and 5,372,852, the disclosures of each of which are totally incorporatedherein by reference, teach that the subtractive primary colorantsemployed can comprise dyes from the classes of Color index (C.I.)Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, and BasicDyes. The colorants can also include pigments, as disclosed in, forexample, U.S. Pat. No. 5,221,335, the disclosure of which is totallyincorporated herein by reference. U.S. Pat. No. 5,621,022, thedisclosure of which is totally incorporated herein by reference,discloses the use of a specific class of polymeric dyes in phase changeink compositions.

Ink sticks currently in use are typically manufactured with a formed tuband flow fill process. In this method, the component dyes and carriercomposition is heated to its liquid state and then poured into a tubhaving an interior shape corresponding to the desired finished ink stickshape. The tub may also be formed with indentations and protrusions forforming keying and coding features in the ink sticks, if desired. Thismanufacturing method allows formation of non-linear shapes, althoughdimensions for the sticks may vary beyond desired tolerance ranges. Poorheight control and stress cracks may be caused by non uniform cooling ofthe ink. Specifically, the outer layer of the molten ink and carrierradiate heat to the outside air and cool more quickly than the interiorportions of the mixture. This situation is worsened by the fact that theupper surface is an open top and cools at a different rate than the tubsurround areas on the sides and bottom. Additionally, features cannot beformed in the upper surface with this method. The top surface nearlyalways solidifies into an uncontrolled, non flat shape such that stickto stick and areas across a stick vary in height. Poor height controlcan allow sticks to be undesirably displaced during handling andtransport and even operation of the printer or imaging device. The flowfill process is used in spite of these limitations because it is veryfast and cost effective. The process of extrusion is another method ofgenerating forms with a lot of mass very quickly and economically.Extrusion, however, generates forms that incorporate features in thelongitudinal direction only. Features perpendicular to the feeddirection cannot be made directly.

SUMMARY

In one embodiment, a method of manufacturing an ink stick for use in aphase change ink jet imaging device comprises heating phase change inkmaterial to an extrusion temperature at which the phase change inkmaterial is in a malleable state. The heated ink material is thenextruded through an extrusion orifice to form an extruded element. Aforging element, is then pressed against the extruded element to form anink stick.

Another aspect comprises a system for manufacturing ink sticks. Thesystem includes a heater for heating phase change ink material to anextrusion temperature. An extruder extrudes the ink material through anextrusion orifice in an extrusion direction to form an extruded element.The system also includes a forming member for pressing a forming elementagainst the extruded element to form an ink stick. As heat is introducedto the system via elevated temperatures of the ink material, variouselements may increase in temperature beyond the ideal. The thermalcontroller may include a cooling unit to selectively effect cooling ornot and to cool all or portions of the extrusion system to establish ormaintain desired temperature of the components and/or extrusionmaterial.

In yet another aspect, a system for manufacturing ink sticks comprise aheater for heating phase change ink material to an extrusion temperatureand an an extruder for extruding the ink material through an extrusionorifice in an extrusion direction to form an extruded element. Thesystem also includes a die for receiving the extruded element; a formingelement for pressing against at least a portion of the extruded elementreceived in the die to substantially fill the die with the extrudedelement and form an ink stick; and a separator for separating the formedink stick from the die. Forming components may be temperaturecontrolled, which generally would include the ability to heat and/orcool, to achieve optimum forming and separating performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a phase change printer with the printertop cover closed.

FIG. 2 is an enlarged partial top perspective view of the phase changeprinter with the ink access cover open, showing a solid ink stick inposition to be loaded into a feed channel.

FIG. 3 is a side sectional view of a feed channel of a solid ink feedsystem taken along line 3-3 of FIG. 2.

FIG. 4 is a perspective view of one embodiment of a solid ink stick.

FIG. 5 is a schematic view of a system for forming solid ink sticks.

FIG. 6 is a side schematic view of an embodiment of the system forforming solid ink sticks of FIG. 5.

FIG. 7 is a top schematic view of an embodiment of the system forforming solid ink sticks of FIG. 5.

FIG. 8 is a side schematic view of an embodiment of the system forforming solid ink sticks of FIG. 5.

FIG. 9 is a top schematic view of an embodiment of the system forforming solid ink sticks of FIG. 5.

FIG. 10 is a schematic view of another embodiment of the system forforming solid ink sticks of FIG. 5.

FIG. 11 is a flowchart for a method of forming solid ink sticks.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

For a general understanding of the present embodiments, reference ismade to the drawings. In the drawings, like reference numerals have beenused throughout to designate like elements.

FIG. 1 shows a solid ink, or phase change, ink printer 10 that includesan outer housing having a top surface 12 and side surfaces 14. A userinterface display, such as a front panel display screen 16, displaysinformation concerning the status of the printer, and user instructions.Buttons 18 or other control elements for controlling operation of theprinter are adjacent the user interface window, or may be at otherlocations on the printer. An ink jet printing mechanism (not shown) iscontained inside the housing. An ink feed system delivers ink to theprinting mechanism. The ink feed system is contained under the topsurface of the printer housing. The top surface of the housing includesa hinged ink access cover 20 that opens as shown in FIG. 2, to providethe user access to the ink feed system.

In the particular printer shown, the ink access cover 20 is attached toan ink load linkage element 22 so that when the printer ink access cover20 is raised, the ink load linkage 22 slides and pivots to an ink loadposition. As seen in FIG. 2, opening the ink access cover reveals a keyplate 26 having keyed openings 24A-D. Each keyed opening 24A, 24B, 240,24D provides access to an insertion end of one of several individualfeed channels 28A, 28B, 28C, 28D of the solid ink feed system (see FIGS.2 and 3).

Each longitudinal feed channel 28A-D delivers ink sticks 30 of oneparticular color to a corresponding melt plate 32. Each feed channel hasa longitudinal feed direction from the insertion end of the feed channelto the melt end of the feed channel. The melt end of the feed channel isadjacent the melt plate. The melt plate melts the solid ink stick into aliquid form. The melted ink drips through a gap 33 between the melt endof the feed channel and the melt plate, and into a liquid ink reservoir(not shown). The feed channels 28A-D have a longitudinal dimension fromthe insertion end to the melt end, and a lateral dimension,substantially perpendicular to the longitudinal dimension. Each feedchannel in the particular embodiment illustrated includes a push block34 driven by a driving force or element, such as a constant force spring36, to push the individual ink sticks along the length of thelongitudinal feed channel toward the melt plates 32 that are at the meltend of each feed channel. The tension of the constant force spring 36drives the push block toward the melt end of the feed channel. The inkload linkage 22 is coupled to a yoke 38, which is attached to theconstant force spring 36 mounted in the push block 34. The attachment tothe ink load linkage 22 pulls the push block 34 toward the insertion endof the feed channel when the ink access cover is raised to reveal thekey plate 26.

A color printer typically uses four colors of ink (yellow, cyan,magenta, and black). Ink sticks 30 of each color are delivered through acorresponding individual one of the feed channels 28A-D. The operator ofthe printer exercises care to avoid inserting ink sticks of one colorinto a feed channel for a different color. Ink sticks may be sosaturated with color dye that it may be difficult for a printer user totell by color alone which color is which. Cyan, magenta, and black inksticks in particular can be difficult to distinguish visually based oncolor appearance. The key plate 26 has keyed openings 24A, 24B, 240, 24Dto aid the printer user in ensuring that only ink sticks of the propercolor are inserted into each feed channel. Each keyed opening 24A, 24B,240, 24D of the key plate has a unique shape. The ink sticks 30 of thecolor for that feed channel have a shape corresponding to the shape ofthe keyed opening. The keyed openings and corresponding ink stick shapesexclude from each ink feed channel ink sticks of all colors except theink sticks of the proper color for that feed channel.

An exemplary solid ink stick 30 for use in the feed channel isillustrated in FIG. 4. The ink stick is formed of an ink stick bodyhaving a bottom, represented by a general bottom surface 52, a top,represented by a general top surface 54, and at least two lateralextremities or sides, represented by general side surfaces 56. The inkstick is illustrated without the key shapes on the lateral sides thatcorrespond to the key plate openings 24A-D through the key plate 26, tosimplify the illustration. The surfaces of the ink stick body need notbe flat, nor need they be parallel or perpendicular to one another.However, these descriptions aid the reader in visualizing, even thoughthe surfaces may have three dimensional topography, or be angled withrespect to one another. The bottom of the ink stick body is a bottomsurface having lateral edges 58 at which the bottom surface 52intersects the lateral side surfaces 56. The ink stick body may beformed in a substantially rectangular block in which the lateral sidesurfaces 56 are substantially parallel one another. Such a rectangularblock form of the ink stick body also includes two end surfaces 60 thatare substantially parallel to one another, and are substantiallyperpendicular to the side surfaces 56. Nevertheless, other shapes of theside and end surfaces are also possible, including curved surfaces.

The ink stick body can have a number of sides other than four. Forexample, the ink stick body can be formed with three, five, or virtuallyany number of side surfaces. These side surfaces need not be equal inlength, nor is the ink stick body necessarily symmetrical about thelateral or vertical centers of gravity. In other shapes, the ink stickbody can have surfaces that are curved. For example, the ink stick bodycan have a cylindrical shape, with the axis of the cylinder parallel thelongitudinal feed direction of the feed channel, parallel the lateraldimension of the feed channel, or perpendicular to both the longitudinalfeed direction and the lateral dimension (vertical).

The ink stick body can also be formed in shapes other than a cubicrectangle. For example, the ink stick can have an elliptical horizontalcross sectional shape, a shape having multiple straight linear sides, oreven a combination of curved and linear sides.

The lateral dimension of the ink stick body between the side surfaces 56is no wider than the lateral dimension of the ink stick feed channel 28between the side walls 42, 44. The lateral dimension of the ink stickbody between the side surfaces 56 is substantially the same as thelateral dimension of the ink stick feed channel 28 between the sidewalls 42, 44, or more specifically only fractionally smaller than thelateral dimension of the ink stick feed channel 28 between the sidewalls 42, 44.

The solid ink stick 30 is formed of a phase change ink compositioncomprising a phase change ink carrier composition and a phase change inkcompatible colorant. The composition should typically be a solid at roomtemperature and have a melting point below the operating temperature ofthe printing equipment that is used to apply the molten ink to asubstrate. When the phase change ink is heated to its molten state, thetemperature of the composition continually rises until the melting pointis reached. At this point, extra energy (latent heat of fusion) isrequired to complete the phase change from solid to liquid. Thetemperature of the phase change ink remains approximately at the meltingpoint until enough heat has been added and the composition hascompletely transitioned from solid to liquid before the temperature ofthe composition begins to rise again. It should be noted that theabsorption of heat by the phase change ink composition may occur morequickly at the surface than it does at internal volumes resulting inuneven melting depending on the shape of the solid ink mass.

Similarly, when the molten phase change ink is allowed to cool, thetemperature of the composition stops falling at or just below thefreezing point. At the freezing point, in order to complete the phasechange from liquid to solid, the energy of the heat of fusion must bewithdrawn. Once completely solidified, the temperature falls steadilyagain. The melting points and freezing points of the phase change inkcomposition vary depending on the properties of the materials used toform the composition. Heat absorption or loss occurs more quickly at thesurface of the composition.

The foregoing description should be sufficient for purposes ofillustrating the general operation of a phase change ink jet printer andthe solid ink sticks utilized by such printers. Referring now to FIG. 5,there is shown an exemplary schematic diagram of a system 600 operableto form solid ink sticks. The system 600 includes an extrusion section604 in which phase change ink is extruded into a generic cross-sectionink form, and a secondary-forming section 608 in which the extruded inkform, while in a hot, malleable or semi-solid state, is processed intoits final profile.

The extrusion section 604 includes an extrusion die 610, an extruder 614for feeding material, under predetermined heat and pressure conditions,into the extrusion die 610, and a molten ink inlet 618 designed toreceive molten phase change ink and feed the ink into the extruder 614.In the exemplary embodiment, the extruder 614 comprises a single screwextruder. Any desired or effective extruder can be employed, includingtwin screw extruders, co-rotating twin screw extruders (wherein bothscrews rotate in the same direction), counter-rotating twin screwextruders (wherein the screws rotate in opposite directions), pistonsand the like. The extruder 614 has a molten ink inlet 618 mounted on topfor receiving phase change ink in a molten (liquid) state and feedingthe molten ink into the extruder 614. The molten ink inlet 618 mayinclude one or more hoppers or feeders for receiving materials to beextruded.

The molten phase change ink is received in the molten ink inlet 618, andthen introduced into the extruder 614. In the extruder 614, the moltenphase change ink is selectively cooled until the ink reaches anextrusion temperature. Heating element(s) (not shown) in the extruderhelp maintain the phase change ink at the extrusion temperature beforeit is fed to the extrusion die. The extrusion temperature corresponds tothe heat level that is conducive to maintain the ink carrier/colorantcomposition at the appropriate malleable state. When the phase changeink is a malleable or semi-solid, a somewhat paste like ink consistencyis established for the composition which allows relatively low pressurefeeding through the extrusion die and a high degree of formability. Thespecific material state, and hence the optimal extrusion temperature, ishighly dependent upon the ink formulation and physical properties, whichmay be non-Newtonian. Achieving and maintaining the ideal temperaturerange for the appropriate consistency benefits from use of a thermalcontroller, i.e., system with a heater and/or cooler, temperaturesensing and/or temperature control unit elements to regulatetemperature, allowing the system to be heated or cooled as required.Heating specifically for the extrusion process may not be necessary ifthe material is furnished directly from a manufacturing process thatincludes mixing of molten material. Cooling may be accomplished with airflow. Cooling action would be selectively performed depending on thetemperature of the material as it nears the extrusion die and/or otherfunctional areas of the system.

A screw 620 in the extruder is operable to feed the phase change inkmaintained at the extrusion temperature to the extrusion die 610 at apredetermined pressure and speed and force the ink through an extrusionorifice (not shown) of the extrusion die 610. The screw 620 may behelical or any other shape operable to mix and flow the semi-solid phasechange ink through the extruder 604. There may be a temperature gradientalong the length of the extruder and the ink within as it is fed throughthe extruder and brought into an ideal temperature for extrusion.

The extrusion die 610 has one or more orifices or apertures (not shown)through which the semi-solid phase change ink is forced (extruded). Theextrusion die 610 is a shaping device with a streamlined orifice thatreduces the extruder's stream of semi-solid phase change ink andgenerates an extruded element having a particular cross-sectional shapeor geometry. The extrusion die 610 may be machined from alloy tool steelor aluminum or any other suitable material. Dies can be made to form avirtually limitless array of shapes and sizes. The extrusion orificecontrols the thickness and width of the extruded material. The materialis extruded through the extrusion die 610 to form an extruded elementhaving a generic cross sectional form which may be circular,rectangular, or any other desired or suitable shape. After leaving theextrusion die 610, the extruded element, while still in a hot semi-solidstate, is directed to the secondary-forming section 608.

As shown in FIG. 6, in one embodiment, the secondary forming section 608comprises a forming station 700 for forming an extruded element into adesired final shape and an extruded element transport 704 fortransporting an extruded element (not shown) in the extrusion directionD. In the exemplary embodiment, the extruded element transport 704comprises one or more conveyor belts configured to move an extrudedelement along the extrusion path from extruder to the forming station ata velocity corresponding to the extrusion velocity.

The forming station 700 includes one or more forming die sets 708 havinga variable cross-sectional internal shape corresponding to the desiredfinal shape of a solid phase change ink stick. Referring to FIG. 7, eachforming die set 708 comprises a pair of mating forging or swagingelements 710, 714. The pair of forging elements 710, 714 cooperates toform a cavity 718 when pressed together having an internal shapecorresponding to the desired final shape of a solid ink stick. Themating dies need not actually touch one another to effect the shapeforming as long as the ink material properties constrain the materialappropriately for subsequent forming influence. Three, four or moreforming dies can be placed radially about the extrusion, oriented suchthat they mate sufficiently to form the desired forming cavity. Forgingcan also include plates with minimal or no internal shape for sizing,flattening, squaring, curving, corner sharpening or other preliminary orfinalization forming. The forging elements 710, 714 are pressed togetherby the movement of a mechanism, which may be cams 720. The forming dies708 follow the flow of the extruded element as it is moving through theforming station by the rotation of cams 724. Arms 728 may be affixed tocams 724 and to the respective forming elements. Cams 724 rotate therebycausing the forming dies 708 to move at the extrusion velocity in theextrusion direction as cams 720 rotate causing the forming elements 710and 714 to be pressed together to enclose the extruded element in thecavity 718 so that the extruded element, while still in a semi-solidstate, at least partially fills the internal shape of the cavity 718 andto at least some extent, takes its form. Once the extruded element isenclosed in the forming dies 708 and formed into the final ink stickshape, rotating cams 720 or an alternative mechanism move to open theforging elements 710, 714 thereby reciprocating the forging dies backinto the starting position. Note that forming rollers and/or dies canform the ink shape in one operation or can partially influence ink shapecontinuously or at progressive forming stations. Single or progressivecontinuous or multiple station forming can be done with any one orcombination of the described or alternative forming methods. It is to beunderstood that when describing an opposing pair of rollers or formingelements, it is inferred that multiple pairs could also be employed.

As shown in FIG. 7, forging elements 710, 714 are situated horizontallywith respect to each other and to the extrusion path and on oppositesides. Alternatively, the pair of forming elements 740 may be orientedvertically with respect to each other and to the extrusion path. In thisembodiment, one of the pair of forming elements comprises a lowerforming element. The lower forming element is positioned on thetransport to receive the extruded element as it is extruded from theextruder. An upper forming element is then pressed down toward the lowerforming element by a piston or some other suitable method, therebyenclosing the extruded element within the forming elements so that theextruded element is modified in form by the internal shape of the cavityestablished by the forming elements. As an alternative to the pistonactivated forming dies, a rotary die set or other motion mechanism maybe used. In this embodiment, the rotary die set comprises rolling diesthat are rotated so as to roll along the outer surface of the extrudedelement as the extruded element moves in the extrusion direction.

The forming station may further comprise a cutting member 730 fortrimming the extruded element at predetermined locations. Cutting member730 comprises a first cutting element 734. To facilitate cutting, thefirst cutting element may be heated to a cutting temperature wherein thecutting temperature may be a temperature that is greater than theextrusion temperature of the extruded element. In order to ensure thecut portions of the extruded element do not bond back together, a secondcutting element 738 may be included that is maintained at a temperaturelower than the cutting temperature of the first cutting element. Thecooler second cutting element 738 runs parallel to the first cuttingelement 734 and is located along the extrusion path between the firstcutting element 734 and the extrusion die 610 spaced just far enoughaway from the hot cutting element 734 to prevent the halves of theextruded material cut by the hot cutting element 734 from bonding backtogether. In the exemplary embodiment, the first 734 and second cuttingelements 738 comprise wires. Alternatively, a flying blade cutter or anyother suitable device or method or combination may be used for trimmingthe extruded element at predetermined locations. Separation of the cutsections may also be facilitated by increasing the travel rate of theleading section after the cut is completed.

The forging station may further comprise guide members 740 formaintaining shape and controlling the position of the extruded elementas it passes through the forming station. The guide members 740 maycomprise roller pairs rotatably mounted adjacent the extrusion pathabout parallel axes in an abutting relation, with periphery of the oneof the pair of rollers engaging, rolling upon and movable relative tothe periphery of the other of the pair rollers. The roller pairs arerotated in opposite rotational directions at a velocity corresponding tothe extrusion velocity. The peripheries of the roller pairs cooperate todefine an opening therebetween that works to maintain the shape of theextruded element and control the position of the extruded element as itmoves along the extrusion path to the forming station. In an exemplaryembodiment, a first pair of rollers 740 may be located adjacent theextrusion die before a cutting member 730, and a second pair of rollers740 may be located on the extrusion path after the cutting member 730.

While all of the elements of the forming section may be mounted andsupported individually along the extrusion path, alternatively, all ofthe elements may be mounted on or included in a single structure. Thisstructure may be provided with a reciprocating cyclic motion to followthe extrusion velocity during the forming stage and then reset to thestarting point for the next cycle.

As this process may benefit from an excess volume of ink to be placed ina given forging die to fill all features, the forging station includesan overflow control (not shown) which may include directing theresultant overflow of ink toward the extruded mass side of the die tominimize or eliminate material that may need to be re-melted or recycledthrough the extruder. Separating the final formed ink sticks from oneanother may be a function of the forming dies or a separate cuttingstation or any other suitable method. Ink formulations and ink sticksize and configurations vary such that specific extrusion temperature,extrusion force, extrusion speed, the number of forging dies and theirtemperature, the number and function of supplementary rolling dies andtheir temperature and other operations and equipment parameters must bevaried to achieve optimum results.

In another embodiment, the secondary forming section 608 comprises aroll forming and swaging station 800. Referring to FIG. 8, the rollforming and swaging station 800 includes an extruded element transport804, a roll forming section 808 and a forging or swaging section 810.The term swaging generally used here for convenience to differentiatefrom forging by suggesting “squeezing” dies that are capable of shapemodification to pre roller formed sections of the extruded materialand/or severing the formed portion of the extrusion material from theextruded portion. The extruded element transport 804 is similar to andhas the same operation as the extruded element transport 704. In thisembodiment, the extruder extrudes a rail of malleable phase change ink(not shown) having the generic cross-sectional form dictated by theextrusion die 610. The extruded element transport 804 is configured totransport the extruded rail of ink through the roll forming and swagingstation 800 at a velocity corresponding to the extrusion velocity.

Referring to FIG. 8, the roll forming section 808 comprises rollerguides 812 for establishing a substantial representation of thelongitudinal shape in the extruded rail of ink. The forming die 820further shapes a portion of the shape transverse to the longitudinal inthe extruded rail of ink. The roller guides 812 comprises roller pairs814, 816, 818 rotatably mounted adjacent about parallel axes in anabutting relation, with periphery of the one of the pair of rollersengaging, rolling upon and movable relative to the periphery of theother of the pair rollers. The roller pairs 814, 816, 818 are rotated inopposite rotational directions at a velocity corresponding to theextrusion velocity. The peripheries of the roller pairs cooperate todefine an opening therebetween that works to both maintain andcontrollably alter the shape of the extruded element and control theposition of the extruded element as it moves along the extrusion path tothe forging station. In an exemplary configuration, as shown in FIGS. 8and 9, roller pairs 814 and 818 are situated so that one roller of thepair is above the extrusion path and the other roller is below theextrusion path for longitudinally shaping the top and bottom of theextruded rail of ink. Roller pair 816 is situated laterally with respectto the extrusion path for shaping the lateral sides of the extruded railof ink. Note that non forming rollers or plates which constrain ormaintain the existing shape of a given area of the extruded material maybe used in conjunction with forming elements of any described oralternative post extrusion forming process to ensure that the inkformation extends to the material areas intended to be shaped ratherthan causing imprecise placement or uncontrolled deformation.

The forming die 820 comprises forming elements 824, 828. The pair offorming elements 824, 828 cooperates to form a cavity 830 when pressedtogether having an internal shape corresponding to a portion of thedesired final shape of a solid ink stick. The forming elements 824, 828are pressed together by the movement of cams 834. Cams 834 rotatecausing the forming elements 824, 828 to be moved toward each topartially enclose the extruded element in the cavity 830 thereby furthershaping a portion of the shape transverse to the longitudinal in theextruded rail of ink.

Once the extruded rail of ink has been longitudinally shaped by theroller guides 812 and forming die 820, the longitudinally shaped rail ismoved to the swaging section 810. The swaging section 810 is configuredto perform a swaging process on the shaped rail of ink to establish thefinal form and cut the rail of ink into individual sticks. Referringagain to FIGS. 8 and 9, the swaging section 810 may comprise a pluralityof swaging members 838. The swaging members 838 may be disposed radiallyat approximately 90 degree intervals about the extrusion path. Each ofthe swaging members 838 may be slidably mounted in a position toradially engage the ink rail to produce the desired swage thereof. Whiletwo such swaging members 838 are shown, the device could have anysuitable number of swaging members 838. Each swaging member 838 at theirradially inner ends carry respective swaging dies 840. Each swaging die840 is configured to impart a predetermined shape and finish forming theshape transverse to the longitudinal shape of the extruded rail of inkand to divide the rail of ink into individual sticks having essentiallythe final desired shape. Note that secondary swaging, or forging may notbe required after roll forming, depending on the intended shape of thefinal ink form.

In one embodiment, the swaging members 838 may be driven in areciprocating manner. As the extruded rail of ink enters the swagingsection 810, the swaging members 838 are radially driven by swagedrivers (not shown) to a position that impresses a shape in the rail andthen returns to a home position. The swage drivers may comprise anyknown or suitable means of driving mechanical elements in areciprocating manner, such as electrically, hydraulically, orpneumatically controlled actuators. Adjacent swaging members 838 may beactuated in alternation so that they can engage the ink rail throughoutits contour without a mutual interference of the dies. The swagingmembers 838 may be actuated simultaneously if there is enough spacingbetween dies.

As noted above, the rail of ink is longitudinally shaped in the rollforming section 808 before it reaches the swaging section 810. Theswaging section 810 is configured to process the extruded rail of inkinto its final form by swaging and separating the rail into individualink sticks. While the swaging members 838 have been described as havinga linear or radial motion, alternatively, a swaging device may beprovided having pivoting or rocker motion or any similar or appropriateaction.

The extrusion and forming process elements would ideally produce an inkstick with all size control and features required of the final form,however, it may be desired to produce a non final form with additionalforming steps in a separate finishing process. As an example, a familyof products using an ink stick set that has only slight featurevariability for the different models, such as a sensing feature, mayencourage fabrication and inventory of a common basic shape that isfurther modified based on sales demands for the intended product. Avariety of form modification methods could be employed to accomplish thefinal shape and/or appearance change, including additional forging orswaging, drilling, milling, sawing, melting with a heated form tool,filling one or more cavities or insets with a plug or molten material,adding nomenclature by stamping or other method, adding a bar code orother optically readable sensing element and so forth.

In yet another embodiment, the secondary forming section 608 comprises afiber processing station 900 for accumulating an extruded element thatis extruded as fibers or filaments 908 (See FIG. 10). In thisembodiment, the extrusion die comprises a spinneret 904 possessing oneor more orifices or apertures (not shown) of a desired diameter toprovide one or more ink filaments 908. As used herein, an extruded inkfiber or filament comprises an extrusion of ink material having at leastone cross-sectional dimension transverse to the extrusion direction thatis sufficiently thin to facilitate flexibility and mechanized handlingof the fiber without breaking. In one embodiment, extruded filaments ofink 908 have a cross-section of less than approximately 6 mm.Flexibility generally improves with smaller filaments and can havecross-sections of 1 or 2 mm or even smaller. The apertures of thespinneret 904 can be of any appropriate desired cross-sectional size andshape. In the exemplary embodiment, the cross-sections of the aperturesare round, but square, triangular, oval or other shaped cross-sectionsare contemplated. In FIG. 10, the apertures in the spinneret arearranged in a single row. However, the aperture pattern in the spinneretmay be of any desired configuration including multiple rows, a matrixpattern or one or more concentric circles.

In one embodiment, the fiber processing station is configured toaccumulate extruded ink filaments by coiling the extruded filamentsaround a coiling element. In this embodiment, individual ink filamentsare passed to a coiling member 924 where the ink filament is woundaround a coiling element 928, such as a winding spool or bobbin, withthe aid of a traverse 930 to form a package. The filament is wound onthe coiling element 928 until an appropriate diameter is reacheddepending on the size of the intended coil package. The coiling member924 may further include a cutting member (not shown) positioned adjacentthe coiling element 914 for cutting the fiber when the appropriatediameter has been reached. The fiber processing station may include acoiling member for each filament extruded through the spinneret. Thus,in one embodiment, a plurality of ink filaments may be extrudedsimultaneously and routed to separate coiling members for accumulation.A variation to this would be to more densely package the filament byusing a fold rather coil approach, such as an overlapping FIG. 8 orzigzag formation.

In another embodiment, the fiber processing station may be configured tocombine a plurality of ink filaments into a multi-fiber ormulti-filament strand of ink before accumulation. In this embodiment,following extrusion through the spinneret 904, a plurality of filaments908 may be collected downstream from the spinneret 904 by a convergingguide 906 before proceeding to a filament arranging or bundling member910. Converging guide 906 may be a pigtail type eyelet, a slottedroller, or any conventional converging or collecting means. Once thefilaments 908 are converged, the filaments 908 may be wrapped around ahub 918 and one or more additional hub, for example, hub 920, to take upand adjust the tension on the filaments 908.

The filaments 908 then proceed to the filament bundling member 910. Thefilament bundling member 910 is configured to bundle the filaments 908into an integrated fiber bundle 914 having a multiple fibercross-section by twisting, spiraling, weaving, braiding, or interlacingand the like. In another embodiment, the fiber bundling member 910 maybe configured to process the filaments 908 into a bonded fiber bundle.In this embodiment, the filaments 908 are bonded together by meltingsuccessive portions of adjacent fibers together or applying a controlledamount of molten ink to portions of adjacent fibers. The bonded fiberbundle may be formed by bonding the entire lengths of adjacent fibers,creating a solid ink “log” with a screw-like periphery. Alternatively,the filaments 908 may be bonded together using any bonding method suchas mechanical bonding, thermal bonding, and chemical bonding.

The integrated or bonded filament bundle 914 may then be passed tocoiling member 924 where the bundle 914 is wound around a coilingelement 928, such as a winding spool or bobbin, with the aid of atraverse 930 to form a package. The bundle 914 is wound on the coilingelement 928 until an appropriate diameter is reached depending on thesize of the intended coil package. The coiling member 924 may furtherinclude a cutting member (not shown) positioned adjacent the coilingelement 914 for cutting the fiber when the appropriate diameter has beenreached. In another embodiment, the accumulator would cut and stack theextruded filament(s) into stick like pieces.

Due to the small cross-section of each fiber in a fiber bundle, a solidink configuration formed of such a bundle exhibits beneficial meltingcharacteristics. For instance, the small cross-sections of the fibersprovides a solid ink stick with increased surface area to volume formore efficient melting and flow rate. Once a fiber bundle 914 of thedesired size and configuration has been formed, the fiber bundle 914 maybe coiled as described above or cut to any length and straightened,bent, or shaped as desired for insertion into final packaging. The finalfilament cross-section size or bundle size may be targeted at variouslevels of stiffness and flexibility, depending on the print engine inkstaging and delivery system requirements.

FIG. 11 is an exemplary flow diagram of a method of forming solid inksticks by extrusion and secondary forming processes. The methodcomprises heating the phase change ink material to an extrusiontemperature (Block 300). As mentioned above, the ink composition ismaintained at a heat level that enables the extruded strand to remain amalleable semi-solid, exhibiting properties between solid and liquid.The ink is then extruded in an extrusion direction through an extrusionorifice to form an extruded element (Block 304). A secondary formingprocess is performed on the extruded element (Block 308).

In one embodiment of the method illustrated in FIG. 11, the secondaryprocess is a forging process (Block 310). In this embodiment, afterextrusion, the extruded element is enclosed in a forging element (Block312). The extruded element has a variable cross-sectional internal shapealong the extrusion direction. The extruded element is then pressedagainst the forging element so that the malleable ink materialsubstantially fills the internal shape of the forging element (Block314).

Alternatively, the secondary forming process is a roll forming andswaging process (Block 316). In this embodiment, after extrusion, theextruded element is roll formed to substantially establish thelongitudinal shape of the extruded element (Block 318). Subsequently,the roll formed extruded element is swaged to establish the final formand cut into individual ink sticks (Block 320). For sticks with singleaxis formed shapes, rolling alone might be sufficient to establish thefinal form.

In yet another embodiment, the secondary forming process comprises afilament processing process (Block 324). In this embodiment, theextruded element comprises an extruded fiber having a cross-sectiongenerally no greater than 12 mm and optimally 6 mm or smaller. Afterextrusion, the extruded filaments are integrated or bonded into afilament bundle by weaving, spiraling, interlacing and the like (Block328). Once the filaments have been integrated or bonded to form abundle, the bundle is accumulated by winding onto a coiling element(Block 330). Specific diameters are less important that the flexibilityof the end configuration based on material properties and environmentalconditions the ink is exposed to at the time of use. Flexible inkmaterial might allow diameters of 25 mm and inflexible material mightrequire diameters less than 6 mm, as example. The criteria forestablishing acceptable size is therefore based more on real worldfracture tendencies of a given system and ink formulation. Ink to be fedin fiber form should be free to be straightened for feed withoutfracturing at operational temperatures and feed rates. Ink fractruinghas exhibited a tendency to be influenced by the rate at which it isuncoiled or straightened, so a larger diameter fiber that is more slowlyfed into a melt device may be less prone to fracturing that a smallerdiameter fed more rapidly at an equivalent melt rate.

Those skilled in the art will recognize that numerous modifications canbe made to the specific implementations described above. Those skilledin the art will recognize that the extruded ink may be forged, rolled,swaged and coiled to any extent and in any combination and into numerousshapes and configurations other than those illustrated. In addition,numerous other configurations of the stations, sections and othercomponents of the ink stick forming system can be constructed within thescope of the disclosure. Therefore, the following claims are not to belimited to the specific embodiments illustrated and described above. Theclaims, as originally presented and as they may be amended, encompassvariations, alternatives, modifications, improvements, equivalents, andsubstantial equivalents of the embodiments and teachings disclosedherein, including those that are presently unforeseen or unappreciated,and that, for example, may arise from applicants/patentees and others.

1. A method of manufacturing an ink stick for use in a phase change inkjet imaging device, the method comprising: controlling a temperaturewithin an extruder to establish a temperature gradient in the extruderto enable phase change ink material within the extruder to reach anextrusion temperature at which the phase change ink material is amalleable semi-solid; extruding the phase change ink material at theextrusion temperature through an extrusion orifice in an extrusiondirection to form an extruded element of phase change ink materialhaving a generic cross-section solid ink form; receiving a portion ofthe extruded element of phase change ink material in a first formingelement positioned on a transport that moves at a velocity correspondingto the velocity at which the extruded element of phase change inkmaterial is extruded from the extrusion orifice; pressing a secondforming element against the extruded element of phase change inkmaterial with a piston to enclose the portion of the extruded element ofphase change ink material received within the first forming elementbetween the first and the second forming elements to at least partiallyform a protrusion or an indentation in the extruded element of phasechange ink material in a direction perpendicular to and vertical to theextrusion direction.
 2. The method of claim 1, the pressing of thesecond forming element further comprising: pressing a forming dieagainst the extruded element in the direction perpendicular to andvertical to the extrusion direction to impart the protrusion or theindentation to the extruded element.
 3. The method of claim 1, thecontrolling of the temperature of the phase change ink material to anextrusion temperature further comprising: heating the phase change inkmaterial to an elevated temperature at which the phase change inkmaterial becomes molten; and selectively cooling the molten phase changeink material to maintain a temperature that enables the phase change inkmaterial to reach the extrusion temperature and be fed through theextrusion orifice along the extrusion direction.
 4. The method of claim1, the extruding of the phase change ink material to form the extrudedelement comprising: extruding the phase change ink material at theextrusion temperature through the extrusion orifice to form a continuouslength of extruded phase change ink material having the genericcross-section solid ink form in the extrusion direction; and cutting thecontinuous length of extruded ink material to form a plurality ofextruded elements, each extruded element having the genericcross-section solid ink form as the extruded ink material moves in theextrusion direction.
 5. The method of claim 1, the pressing of theforming element against the extruded element having the genericcross-section solid ink form further comprising: pressing a key elementconfigured on the forming element to form the protrusion or indentationon the extruded element.
 6. A system for manufacturing ink sticks, thesystem comprising: a thermal controller configured to control atemperature within an extruder to establish a temperature gradient inthe extruder to bring molten phase change ink material within theextruder to an extrusion temperature at which the phase change inkmaterial is a malleable semi-solid; an extruder configured to extrudethe phase change ink material through an extrusion orifice in anextrusion direction to form an extruded element having a genericcross-section solid ink form; a transport configured to receive aportion of the extruded element from the extruder in a first formingelement positioned on the transport and move the portion of the extrudedelement in the first forming element in the extrusion direction at avelocity at which the extruded element was extruded from the extrusionorifice; and a second forming member configured with a piston thatoperates to press the second forming element in a directionperpendicular to and vertical to the extrusion direction against theextruded element to enclose the portion of the extruded element betweenthe first and the second forming elements to at least partially form aprotrusion or indentation in the portion of the extruded elementenclosed between the first forming element and the second formingelement.
 7. The system of claim 6, further comprising: a cutting memberconfigured to cut the extruded element having the generic cross-sectionsolid ink form into discrete lengths to produce a plurality of extrudedelement portions for being received in a plurality of first formingelements, each extruded element portion having a generic cross-sectionsolid ink form.
 8. The system of claim 6, the first forming memberfurther comprising: a plate configured to press against the portion ofthe extruded element in the first forming element in the directionperpendicular to and vertical to the extrusion direction to at leastpartially form the protrusion or the indentation.
 9. The system of claim8, the plate further comprising: at least one key feature for forming atleast one keying element in the extruded element in the first formingelement.